Power Fc Injector Settings

[JimX]

I've done a search on +injector* +delay and it didn't turn anything relevant up so hopefully this is a new question.

Can anyone explain how to set the injector settings on the PowerFC? I had been told previously that it's supposed to be a percentage based on your stock rating. For example, R33 GTS-t stock is 370cc, so when fitting 550's it would be 67% to give the same injector pulse as stock. But I've read elsewhere that 550's should be set to around 85% or so. In my current tune, they've all been set to 75%, but this is in conjunction with an adjustable fuel pressure regulator so that probably has something to do with it (no I don't know what the pressure's set to, waiting on delivery of gauge). Or have I got the idea behind this setting all completely wrong?

The other thing is the delay setting. Again, I've been told a couple of different things. I *think* read somewhere that it should be current injector size divided by stock, expressed as a negative millisecond delay. So that would be 1.48 for 550's, rounding off to -0.01 or -0.02? Or if I got that calculation around the wrong way then maybe it should be -0.67ms. My tuner had left this setting on zero and it seems to drive ok. What's the purpose of this setting and if I should change it and why?

Thanks again in advance (it feels like I'm doing a thesis on powerFC's with all these questins I'm asking!)